Wonderful tool !!! I'm building some Dashboards and I'm facing an issue with unassigned tasks.

One of these dashboards is a chart of tasks categorized by asignee. The problem is that all unassigned tasks are in this chart as well (they are displayed which is good) but not displayed in the legend.

Would there be a kind of way to display these Unassigned tasks as a category with a legend in addition to my assignee ?